Greases are widely used in lubrication of bearings and other structural components. An effect called false brinelling occurs in the circumstances with relatively small displacements between rolling parts and the raceway of the bearing rings, whereby false brinelling is found in incomplete contacts. Further, an effect called fretting is found in complete contacts. Fretting relates to bearing seat interfaces of which the mating surfaces are oscillating at small amplitudes. False brinelling and fretting can result in considerable damage. Up to now, commercially available greases particularly in rolling bearings are lacking in protection against false brinelling and fretting.
So one problem addressed by the present invention is to find a suitable lubricant for a use between two elements being movable against each other, so that the elements are also protected against false brinelling and fretting.
Thereby the invention is based on the cognition, that the lubricant according to the present invention provides a lubricant having well-performing properties in conventional bearing operation (over rolling) also provides excellent anti-false brinelling properties and protects mating components against fretting and fretting corrosion.
Furthermore the invention is based on the cognition, that grease lubrication functions well at relatively large amplitude oscillations. At smaller displacement amplitudes greases face severe difficulties to provide proper lubrication to the mating surfaces. It has been found that the phosphate coating is not sufficient for preventing false brinelling. Thereby adhesion of phosphates is insufficient resulting in premature removal from the rolling bearing component. So the phosphate layer will simply be wiped away during the first oscillations and after that there is no lubrication to prevent damage to the related parts. The phosphate layer with grease lubrication will not offer sufficient protection against false brinelling especially not in the so-called partial slip regime.